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ibernate
多对一连接表单向关联
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一、模型介绍
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多个人（Person）对应一个地址（Address）。
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二、实体（省略getter、setter方法）
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public class Personn1tab {
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private int personid;
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private String name;
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private int age;
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private Addressn1tab addressn1tab;
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public class Addressn1tab {
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private int addressid;
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private String addressdetail;
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三、表模型
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mysql> desc address_n1tab;
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+---------------+--------------+------+-----+---------+----------------+
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| Field | Type | Null | Key | Default | Extra |
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+---------------+--------------+------+-----+---------+----------------+
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| addressid | int(11) | NO | PRI | NULL | auto_increment |
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| addressdetail | varchar(255) | YES | | NULL | |
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+---------------+--------------+------+-----+---------+----------------+
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mysql> desc join_n1tab;
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+------------+---------+------+-----+---------+-------+
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| Field | Type | Null | Key | Default | Extra |
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+------------+---------+------+-----+---------+-------+
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| personid | int(11) | NO | PRI | | |
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| addressn1tab | int(11) | YES | MUL | NULL | |
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+------------+---------+------+-----+---------+-------+
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mysql> desc person_n1tab;
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+----------+--------------+------+-----+---------+----------------+
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| Field | Type | Null | Key | Default | Extra |
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+----------+--------------+------+-----+---------+----------------+
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| personid | int(11) | NO | PRI | NULL | auto_increment |
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| name | varchar(255) | YES | | NULL | |
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| age | int(11) | YES | | NULL | |
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+----------+--------------+------+-----+---------+----------------+
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四、生成的SQL脚本
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CREATE TABLE `address_n1tab` (
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`addressid` int(11) NOT NULL auto_increment,
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`addressdetail` varchar(255) default NULL,
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PRIMARY KEY (`addressid`)
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) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=gbk;
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CREATE TABLE `join_n1tab` (
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`personid` int(11) NOT NULL,
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`address11fk` int(11) default NULL,
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PRIMARY KEY (`personid`),
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KEY `FKAC780AAADAE3A82C` (`personid`),
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KEY `FKAC780AAAC6242A64` (`address11fk`),
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CONSTRAINT `FKAC780AAAC6242A64` FOREIGN KEY (`address11fk`) REFERENCES `address_n1tab` (`addressid`),
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CONSTRAINT `FKAC780AAADAE3A82C` FOREIGN KEY (`personid`) REFERENCES `person_n1tab` (`personid`)
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) ENGINE=InnoDB DEFAULT CHARSET=gbk;
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CREATE TABLE `person_n1tab` (
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`personid` int(11) NOT NULL auto_increment,
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`name` varchar(255) default NULL,
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`age` int(11) default NULL,
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PRIMARY KEY (`personid`)
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) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=gbk;
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五、映射方法
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<hibernate-mapping>
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<class name="com.lavasoft.dx._n_1_tab.Personn1tab" table="PERSON_n1tab">
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<id name="personid">
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<generator class="identity"/>
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</id>
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<property name="name"/>
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<property name="age"/>
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<!--
使用join元素显式确定链接表-->
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<join table="join_n1tab">
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<!--
映射关联所用的外键-->
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<key column="personid"/>
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<many-to-one name="addressn1tab"/>
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</join>
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</class>
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</hibernate-mapping>
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<hibernate-mapping>
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<class name="com.lavasoft.dx._n_1_tab.Addressn1tab" table="ADDRESS_n1tab">
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<id name="addressid">
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<generator class="identity"/>
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</id>
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<property name="addressdetail"/>
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</class>
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</hibernate-mapping>
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六、测试方法
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public class Test_n1tab {
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public static void main(String[] args){
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Personn1tab p1=new Personn1tab();
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Personn1tab p2=new Personn1tab();
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p1.setAge(21);
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p1.setName("p1");
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p2.setAge(23);
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p2.setName("p2");
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Addressn1tab add=new Addressn1tab();
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add.setAddressdetail("
郑州市经三路");
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p1.setAddressn1tab(add);
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p2.setAddressn1tab(add);
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Session session=HibernateUtil.getCurrentSession();
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Transaction tx=session.beginTransaction();
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session.save(add);
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session.save(p1);
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session.save(p2);
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tx.commit();
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HibernateUtil.closeSession();
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}
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}
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七、测试结果
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1) :
正常保存. 推荐这么干!
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session.save(p1);
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session.save(p2);
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Hibernate: insert into ADDRESS_n1tab (addressdetail) values (?)
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Hibernate: insert into PERSON_n1tab (name, age) values (?, ?)
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Hibernate: insert into join_n1tab (address11fk, personid) values (?, ?)
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Hibernate: insert into PERSON_n1tab (name, age) values (?, ?)
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Hibernate: insert into join_n1tab (address11fk, personid) values (?, ?)
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2) :
正常保存.
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session.save(p1);
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session.save(p2);
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session.save(add);
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Hibernate: insert into PERSON_n1tab (name, age) values (?, ?)
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Hibernate: insert into join_n1tab (address11fk, personid) values (?, ?)
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Hibernate: insert into PERSON_n1tab (name, age) values (?, ?)
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Hibernate: insert into join_n1tab (address11fk, personid) values (?, ?)
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本文转自 leizhimin 51CTO博客，原文链接：http://blog.51cto.com/lavasoft/39322，如需转载请自行联系原作者
